docs: def _normalize_percent_rgb(value):
      """
      Internal normalization function for clipping percent values into
      the permitted range (0%-100%, inclusive).
  
      """
      percent = value.split(u'%')[0]
      percent = float(percent) if u'.' in percent else int(percent)
  
      return u'0%' if percent < 0 \
          else u'100%' if percent > 100 \
          else u'{}%'.format(percent)